Process for producing a bulky yarn

ABSTRACT

A method of producing a bulky yarn having a controlled residual torque, which comprises subjecting a thermoplastic synthetic filament yarn to a series of twisting, heat-setting on a first heater, and untwisting, feeding the yarn into a second heater while rotating it by means of a fluid nozzle and re-heat-setting the yarn in the second heater, the yarn being maintained in a substantially relaxed state during the rotation by the fluid nozzle and the re-heat-setting by the second heater.

United States Patent [191 Maruyama et al.

PROCESS FOR PRODUCING A BULKY YARN Inventors: Fumishige Maruyama; Toshiyuki Yasui; Kaoru Asada, all of Komatsu, Japan Teijin Limited, Osaka; Teiiin Modern Yarn Co., Ltd., Komatsu-shi, lshikawa-ken, both of, Japan Filed: Dec. 17, 1971 Appl. No.: 209,115

Assignees:

Foreign Application Priority Data Dec. 19, 1970 Japan 45-114882 U.S. Cl. 57/157 TS, 57/34 HS int. Cl. D02j 1/20 Field of Search 57/34 R, 34 B, 34 HS, 157 TS, 57/157 R, 157 MS, 157 F Primary Examiner-Donald E. Watkins Attorney, Agent, or Firm-Sherman & Shalloway [57] ABSTRACT A method of producing a bulky yarn having a controlled residual torque, which comprises subjecting a thermoplastic synthetic filament yarn to a series of twisting, heat-setting on a first heater, and untwisting, feeding the yarn into a second heater while rotating it by means of a fluid nozzle and re-heat-setting the yarn in the second heater, the yarn being maintained in a substantially relaxed state during the rotation by the fluid nozzle and the re-heat-setting by the second heater.

9.0 aims, 11 Drawing Figures r .4. r\\\\\\\\\\\\\\ \\\\\w PROCESS FOR PRODUCING A BULKY YARN This invention relates to a process for producing a yarn having high bulk and controlled residual torque. More specifically, the invention relates to a process for producing a bulky yarn having controlled residual torque by subjecting a thermoplastic synthetic filament yarn to a continuous series of twisting, heat-setting, and untwisting steps, and then again heat-treating it in a substantially relaxed condition.

A number of methods have been proposed previously for the production of bulky yarns. These methods, for example, include a method comprising three steps of heating, heatsetting, and untwisting (German Pat. No. 618,050 and Japanese Pat. No. l30,429), the so-called false-twisting method in which heating, heat-setting, and untwisting are performed in one step (British Pat. No. 424,880), a modified false twist method wherein bulky yarns obtained by false-twisting are simultaneously heat-set, and a method wherein the bulky yarns obtained by false-twisting are again heat-set by heating.

The bulky yarns produced by these methods have different forms of crimp or yarn quality such as crimpability. These conventional methods, however, cannot at all exert a free control of the residual torque while retaining the desirable bulkiness.

Yarns produced by a series of twisting, heatsetting, and untwisting steps have a very large residual torque. In order to reduce the residual torque, a modified falsetwisting method (to be referred to as the two-heater method) in which the yarn is continuously passed between two heaters on a false twisting machine to set the crimps, and a method (to be referred to as the package set method) wherein a cheese of a falsetwisted yarn is heat-treated to set the crimp have been proposed.

According to these methods, there is a close correlation between the bulk and the residual torque of the resulting yarns, and it has been difficult to control the bulk and the residual torque independently of each other. For some applications, it is necessary to reduce the residual torque to substantially zero, or to increase it. However, the realization of this was extremely difficult with the conventional methods.

Methods of reducing the residual torque have been proposed in Japanese Patent Publications Nos. 16,688/64, 28,260/68, and 72,20/71.

The specification of Japanese Patent Publication No. 16,688/64 proposes the production of a bulky yarn that can be handled in the form of a single yarn by using a contact heater having a curved surface in the reheating process and passing the yarn between a first hollow spindle and a second hollow spindle. By this method, however, sufficient bulkiness cannot be imparted to the yarns.

The method disclosed in the specification of Japanese Patent Publication No. 28,260/68 comprises falsetwisting and heat-setting at least two yarns doubled with each other, applying to the yarns after passage of a falsetwisting spinner a weak twist in a direction opposite to the false-twisting direction before they reach a twistsetting pin or a spreading pin, re-heatsetting the bundle of yarns at this point, and then spreading the bundle yarn into the individual yarns. This method, however, has defects in operation, and since the yarn is treated under tension by the second heater, sufficient bulkiness cannot be imparted to the yarn.

According to Japanese Patent Publication No. 7,220/71, the above-mentioned package setting method is continuously performed. Specifically, a yarn false-twisted by a first heater is treated continuously with heated steam at an overfeed rate of 0 to 30 percent. This, however, has operational difficulties, and cannot reduce the residual torque to the extent achieved by the package set method.

An object of the present invention is to overcome the difficulties of the prior art methods described above, and to provide a novel method of continuously producing bulky synthetic filament yarns whose residual torques have been freely controlled without impairing the bulkiness of the yarns.

According to the present invention, a method is provided of producing a bulky yarn of controlled residual torque, which comprises subjecting a yarn to a series of twisting, heat-setting on a first heater, and untwisting, feeding the yarn into a second heater while rotating it by a fluid nozzle and re-heatsetting the yarn in a second heater, the yarn being maintained in a substantially relaxed condition during the rotation by the fluid nozzle and re-heatsetting by a second heater.

The reason why a yarn which has been subjected to the steps of twisting, heat-setting, and untwisting has a residual torque is that the yarn has the propensity to return to the state at the time of heatsetting. Similarly, the yarn rotated at the time of re-heatsetting tends to return to the state at the time of re-heating after untwisting. Therefore, generally, when the twisting direction at the time of a first heat-setting is opposite to the torque direction of a second heat-setting, the residual torque is balanced, and the yarn has a reduced residual torque and becomes a socalled non-torque crimped yarn free from residual torque. Conversely, when the twisting direction of the first heat-setting is the same as the torque direction of the second heat-setting, the residual torque of the yarn increases to give a crimped yarn useful as creped woven fabrics such as de chin.

While a reduction in crimpability has been a problem in the conventional two-heater method, this has been solved by the present invention using a fluid nozzle capable of twisting the yarn in a relaxed condition, whereby at the time of the second heat-setting, it is possible to heat set the crimped yarn without stretching -therefore in a condition in which sufficient bulk can be developed. Accordingly, the present invention provides a bulky yarn of increased torque capable of being applied to non-torque or de chin, etc.

The preferred embodiment of the present invention will be described with reference to the accompanying drawings in which:

FIG. 1 is a schematic view illustrating the entire process of the method of the present invention;

FIG. 2 is a sectional view showing one embodiment of the fluid nozzle;

FIG. 3 is a view illustrating the relative positions of the second heater, fluid nozzle and twist-nipping point;

FIGS. 4-7 show vertical views of preferred embodiments of a second heater used in the invention.

FIGS. 8-11 show end views of FIGS. 4-7, respectively.

One example of the entire process of the invention will be described with reference to FIG. 1.

Referring to FIG. 1, a starting yarn 2 is withdrawn from a bobbin 1 by a pair of feed rollers 3, and delivered onto a first heater 4. The yarn is twisted by a spindle 5, and subjected to a first heat-setting by the first heater 4. The yarn is delivered onto a second heater 7 by first delivery rollers 6 while overfeeding. At the time of re-heatsetting by the second heater, the yarn is rotated by a fluid nozzle 8, delivered by second delivery rollers 9, and then wound up on a cheese 11 by a windup roller to thereby provide the intended product. In this process, the yarn must be naturally or forcedly cooled between the outlet of the first heater 4 and the spindle 5, and between the outlet of the second heater 7 and the second delivery roller 9.

As a twist-nipping point in re-heatsetting, the first delivery rollers 6 and the second delivery rollers 9 are helpful. The step of twisting, heat-setting on the first heater, and untwisting can be performed by any known method.

The most characteristic feature of the method of the present invention is that a yarn which has been subjected to such twisting, first heatsetting and untwisting is fed to the second heater while being rotated by a fluid nozzle, and during this time, the yarn is maintained in a substantially relaxed condition. This substantially relaxed condition means that a tension in excess of 0.070 g/denier is not exerted on the running yarn. The application of a tension not in excess of 0.050 g/denier is preferred, and most preferably, the tension should not exceed 0.025 g/denier. In order to realize such low tension, it is necessary to adjust the overfeed rate of the yarn to the second heater to above 4 percent. The preferred overfeed rate is at least 6 percent, and more preferably, it is at least 10 percent. There is no particular upper limit of the overfeed rate, but from the standpoint of operation efficiency, it is usually 60 percent, preferably 50 percent, and more preferably 40 percent. Thus, without reducing the bulkiness intended by the present invention, it is possible to obtain a yarn having a freely controlled residual torque with great ease.

In order to maintain the yarn in a substantially relaxed condition, the use of a fluid nozzle and the avoiding of a full contact of the running yarn with the wall surface of the second heater are required in the present invention.

The fluid nozzle has a function of introducing a stream of fluid in the non-axial direction into a twisting path and bringing it into direct collision with a filament yam which has been fed into the twisting path and is moving at high speed under low tension, eccentrically with respect to the longitudinal axis of the yarn, to thereby give twists to the yarn. Fluid nozzles per se based on such theory have previously been used for twisting yarns, and are well known. These fluid nozzles differ somewhat in structure, but all of them can be used in the present invention. Several of the preferred fluid nozzles are disclosed in Japanese Patent Publications Nos. 11,348/61, 11,349/61, 11,350/61 and 11,266/62. Of these, the nozzles disclosed in Japanese Patent Publications No. l 1,266/62 are especially preferred, and has the structure as shown in FIG. 2.

Referring to FIG. 2, a fluid introduced from a fluid inlet 12 enters a hollow portion 15 of a main nozzle body 14. The hollow portion 15 is provided eccentrically with a flow passageway 13, so that the fluid which has flowed into the hollow portion 15 is rotated. The rotating direction can be freely changed by changing the position of the flow passageway 13.

The fluid nozzle may be provided before or after the second heater. Generally, it is preferred to provide it after the second heater in view of the installation space of the nozzle and the lowering of the temperature of the heater due to the inflow of the fluid.

Examples of the fluid that can be used in the present invention are inset gases such as nitrogen, neon, crypton, argon, helium, carbon dioxide gas, or air, and steam or water. Because of availability and ease of handling, air is preferably used. The pressure of the fluid can vary according to the kind of fluid, the structure of the fluid nozzle, and the desired torque, but is generally in the range of about 0.05 kg/cm (gauge) to 2.0 kg/cm (gauge).

The second heater used in the invention is of any type which can maintain the yarn in a relaxed condition within the heater and does not permit the full contact of the yarn with the heater. Examples of the second heater include pipe heaters in which the yarn path is hollow, slit type heaters in which the yarn path is a slitlike opening in the direction of yarn travel, or heaters of the type wherein a yarn guiding wire or plate is secured to a desired place on the curved surface in the direction of yarn travel so as to avoid the full contact of the yarn with the heater. Generally, the pipe heaters which are straight in the direction of yarn travel are preferably used. v

The full contact type heaters which have previously been used as the second heater cannot attain the substantial relaxed condition as intended in the present invention since the running yarn is held taut due to the contact resistance on their surfaces. In view of this, it is desirable to pass the yarn through the hollow part of the pipe so as to avoid contact with the wall surface of the pipe heater. Smooth industrial operation of such yarn passing is not so easy. If, however, the yarn is contacted only at the inlet and outlet ends of the heater, such operation becomes easy, and the yarn can be maintained in a substantially relaxed condition.

The vertical and cross sectional surfaces of the four preferred embodiments of the second heaters are illustrated in FIGS. 4-7 and 8-11, respectively. These heaters are of the type which permit contact of the yarn only at the inlet and outlet ends. In FIGS. 4-7, the heater is shown at 7, and the running yarn at 2. The heaters of FIGS. 4, 5, and 6 do not include a guide for the running yarn, and the heater of FIG. 7 includes guides (16). The positions of contact of the yarn with the heater are indicated by f and f. The heaters of FIGS. 5 and 6 are obtained by providing the pipe heater 4 with a slit or an opening of larger width, and permit easy yarn stringing operation. Guides can be provided in the heaters of FIGS. 5 and 6 also, as in FIG. 7.

The contact positions of the yarn at the inlet and outlet ends of the heater are such that within the inner space of the heater, the yarn does not come into full contact with the wall surface of the heater. For example, when a heater having an inner space with a circular cross section is used, the two contact points should oppose each other as much as possible. It is however preferred that when the inlet contact point (1) and the outlet contact point (1" are projected on a cross sectional plane perpendicular to the axis of the heater, an angle formed by lines connecting two projected points respectively with the center of the circle is at least preferably at least more preferably at least When these two contact points are selected so as to be situated opposite to each other, the angle is 180. The above condition is applicable to a heater of the type wherein the shape of the cross sectional surface of its inner space is an ellipse in which the ratio of the long axis to the short axis is not more than 20. While the above discussion has been directed primarily to heaters of circular or elliptical cross section, the shape of the heater is not limited to these shapes. The requirement is that the yarn should not be placed under excessive tension by excessive contact with the wall surface of the heater.

According to the methods involving a fluid nozzle, the yarn is twisted by a rotating stream in the twisting path of the fluid, and therefore, the position of securing the fluid nozzle is important in performing the method of the invention industrially.

It is very desirable that in order to have the rotating ability by the fluid nozzle exhibited effectively and stably and render the residual torque and crimpability of the yarn obtained in each spindle in a multi-spindle operation substantially uniform, the following conditions must be satisfied with respect to the fluid nozzle, the second heater, and the distance and angle between the twist-nipping points. These relations are shown schematically in FIG. 3.

These relations are:

1 a 1.0 (cm) wherein I is the distance between the outlet contact end of the yarn in the second heater and the center of the fluid nozzle inlet, 6 is an angle formed by the line connecting the outlet contact end with the center of the inlet of the twisting path, and the axial line of the second heater at the outlet contact end, 1 is the distance between the center of the nozzle twisting path and the twist-setting points, and 0 is an angle formed by the line connecting the center of the nozzle twisting path outlet and the axial line of the nozzle at the outlet center. When woven or knitted fabrics are produced using the yarn obtained under these conditions or such yarn is scoured and dyed, products of very good quality can be obtained. Thus, the method of the present invention is very advantageous industrially.

Furthermore, by employing a fluid nozzle meeting these requirements, the hydrodynamic resistance of the fluid within the fluid nozzle and other yarn twisting portions in contact with yarn guides is very stable and the amount of fluid to be used for giving the same residual torque is also small. Furthermore, the wear of the material of structure on the surface in contact with the yarn is very small, and it is possible to use an inexpensive material of low wear resistance, and it becomes possible to produce a bulky yarn having any desired residual torque with economical advantage.

If the distance (1,) between the outlet of the heater and the nozzle is below 1.0 cm, the residual torque given by the fluid nozzle becomes extremely unstable, and there is a reduced efficiency of operation of passing the yarn through the fluid nozzle, etc. Therefore, the preferred 1, is at least 1.0 cm, preferably about 1.5 cm. There is no upper limit for l, but with increasing 1,, more space is needed on the falsetwisting machine.

Therefore, the upper limit of the distance is generally cm, preferably 10 cm.

The angle 6, is preferably larger than 0. if the angle 6 is below 0, the residual torque differs greatly from spindle to spindle. On the other hand, it the angle exceeds 20, the twisting effect by the fluid decreases, and it results in a reduction in crimpability of the yarn. The especially preferred angle 6 is not more than 15".

If the distance 1 becomes large, torque effect changes abruptly although differing depending upon the fluid pressure, and there is a setback also with respect to installation space. The advantageous distance 1 is not more than 30 cm, preferably, not more than 30 The angle 6 is within the range of 0 to 20 for the same reasons as mentioned with respect to the angle 6 The Reynolds number of fluid at the torque twisting portion in the present invention can be very small. By applying a Reynolds number as small as 1,000 to 5,000, the intended yarn having controlled residual torque can be obtained.

It has been found as a result of a number of experimental results that by applying a Reynolds number larger than 1,000 and satisfying the following equation when torque is given to the yarn by a fluid nozzle in the direction opposite to the twisting direction in the first step, a yarn of high bulk and substantially free of torque can be produced.

(-00433 T 15.13) (2.02 X l0 )De"- a Re a (0040 T 0.045 T 4.2) (0.877 X 10 X D 0.3fi6) wherein Re is Reynolds number,

T is the temperature of the first heatsetting(C), T is the temperature of the second heatsetting(C) De is the denier size of the yarn.

When the Reynolds number is considerably small, the torque twisting effect is small, and the residual torque in the twisting direction in the first heater is reduced by a fluid nozzle. Therefore, a non-torque bulky yarn cannot be obtained. On the other hand, if the Reynolds number becomes large, a residual torque is given in the opposite direction in an amount more than the residual torque in the twisting direction on the heater, and the residual torque in the opposite direction increases. As a result, it is impossible to obtain a nontorque bulky yarn. As shown above, the Reynolds number is affected by the temperature of the first and second heaters, and the denier size of the yarn.

The upper limit of the Reynolds number is not affected by the temperature of the first heater, and is given as a function of the temperature of the second heater and the denier size of the yarn. With increasing heater temperature (T and decreasing denier sizes, non-torque bulky yarns can be obtained with smaller Reynolds number.

On the other hand, the lower limit of the Reynolds number is given as a function of the temperatures of the first and second heaters, and the denier size of the yarn. Non-torque bulky yarns are obtained with higher temperatures of the first heater, lower temperatures of the second heater, and smaller denier sizes of the yarns. These factors define the lower limit of the Reynolds number.

Such a tendency is readily demonstrated by the fact that in the absence of a fluid nozzle, the residual torque of a yarn becomes larger with higher temperatures of the first heater and lower temperatures of the second heater; and conversely that it is smaller with lower temperatures of the first heater and higher temperatures of the second heater.

The especially preferred range of Reynolds number applicable to the production of the non-torque yarns is expressed by the following equations.

Generally, the temperature of the heater can be expressed by the surface temperature in the case of the contact-type heaters, and by the temperature of the gas phase part in the case of the non-contact type heaters. However, temperature distribution sometimes occurs in the direction of the yarn travel in the heater according to some heating methods using the heaters. For example, in the case of heating with steam or heat-media, such temperature distribution relatively seldom occurs, and the temperature distribution is substantially uniform. On the other hand, in the case of electrical heating, considerable temperature distribution occurs, and

, therefore, the temperature of the heater should be expressed by an area average temperature in the direction of the travel of the yarn. Generally, it can be simply expressed by the temperature of the central part of the heater.

The filament yarns used in the present invention are thermoplastic synthetic fibers. Among them, polyester, polyamide, polyolefin, polyacrylonitrile, and acetate yarns are advantageously employed either alone or in combination. The method of the present invention is especially advantageously applied to polyamide and polyester yarns, especially polyethylene terephthalate and poly-e-caproamide yarns, or mixtures of these yarns.

The thermoplastic filament yarns used in the invention may be any filament yarn such as monofilaments or multifilaments although differing somewhat with denier size. Generally, the method of the invention is advantageously applied to multifilaments. The denier size of the useful filament yarn is to 300 denier, preferably 50 to 200 denier, more preferably 70 to 150 denier.

The temperatures of the first and second heaters may be above the glass transition point up to the melting point of the yarn, preferably from about 160 C. up to the melting point. In the case of a polyethylene terephthalate yarn, temperatures in the range of 160 to 230 C. can be effectively employed. The temperature of each heater can be chosen according to the desired bulkiness.

The effective heat-treating time at the heater differs depending upon the type, denier size and number of filaments of the thermoplastic synthetic filament yarn used and the performance of the heater and heating method. Generally, it is at least 0.2 second, preferably at least 0.3 second, especially preferably at least 0.4 second. There is no upper limit, but for economical reasons, the upper limit is usually set at about 3 seconds, preferably about 1.5 second, especially preferably about 1 second. Accordingly, the first and second heaters can be chosen so that they satisfy the effective heat-treating time requirements mentioned above. The

length of each heater can therefore be one which meets such conditions. These conditions are applicable both to the first and second heaters.

In a cooling zone after the first heater and the second heater, the yarn is preferably cooled below the glass transition temperature of the yarn. Since the fluid nozzle mentioned above is used in the present invention, heat dissipation from the yarn achieved by the rotating fluid can be effectively facilitated, and therefore, a much larger cooling effect can be achieved than natural cooling.

The number of twists in the first step twisting is defined generally by the l-Ieberleins equation disclosed in British Pat. No. 890,992 or the Koechlins equation although differing according to the end use of the product yarn. For example, the number of twist T [T/M] is given by the following equation T=aC/ De wherein a is a twist coefficient, C is a constant determined by the yarn material such as polyethylene terephthalate or poly-e-caproamide, and De is the denier of the yarn. The twist coefficient is 0.5 to 1.10, preferably from 0.80 to 1.05.

On the other hand, there is no particular limitation on the speed of the running yarn. Although different according to the type of the false-twister, processing conditions, and the yarn, the speed is usually 60 meters per minute or above. The upper limit is automatically set according to the above-mentioned conditions.

The direction of yarn travel is not particularly limited (e.g., the yarn can be travelled upwardly, downwardly, or even horizontally).

The invention will be described further by the following Examples and Comparative Examples.

In the Examples, the residual torque is the number of twists of a yarn at a time when a load of 2 mg per denier is applied to the yarn and the yarn stops rotating. The measured value is one per 25 cm, and the rotating force in the Z direction is positive.

The crimp shrinkage is measured as follows:

The length (I of a yarn is measured under a load of 202 mg/de, and then the yarn is treated with boiling water for 20 minutes under a load of 2 mg/de. The yarn is spontaneously dried for one day and night in the absence of load, and then the length (1 is measured under a load of 202 mg/de. Then-under a load of 2 mg/de, the length (l of the yarn is measured. The crimp shrinkage is expressed by the following equation.

Crimp shrinkage =1 l /l X If the yarn is a poly-e-caproamide yarn, the heavier load used is 102 mg/de instead of 202 mg/de.

EXAMPLES 1 TO 8 A l50-denier/30 filament semidull yarn of polyethylene-terephthalate was crimped at an overfeed rate of 4 percent, and a yarn speed of meters/min. in the productional process shown in FIG. 1. The number of false twists was 2670 (T/M), and the false-twisting direction Z. The heater used was a curved surface contact type (heater length l m) was a heating temperature of the first heater being adjusted to 220 C. Then, the yarn was passed through the second heater and the center of the fluid nozzle at an overfeed rate of 17 percent. The second heater is a pipe type having a circular vertical section in axial direction. The heating temperature of the second heater was 220 C., and the heater length was 50 cm. The fluid nozzle used was of the type shown in FlG. 2 which rotated in the S direction. As the fluid, air was used, and the pneumatic pressure at the inlet 13 of the nozzle was adjusted as indicated in Table 1. The results are also shown in Table 1.

Table 1 Pneumatic Residual Crimp Examples Pressure(kg/cm G) torque Shrinkage EXAMPLE 9 AND COMPARATIVE EXAMPLES 1, 2 AND 3 The procedure of Example 1 was repeated except that the overfeed rate was 3 percent, the yarn speed was 105 meters/min, the number of twist of 2,500 (T/M), the temperature of the first heater was 210 C., the temperature of the second heater was 215 C., the second overfeed rate was 20 percent, and the pneumatic pressure was 0.12 kg/cm G. For comparative purposes, the fluid nozzle was removed in the above Example, and the yarn was simply heat-set on the second heater (comparative Example 1); a hollow spindle was provided in place of the fluid nozzle 5, and also a contact heater was provided (the number of false twist 2040 (T/M), the false-twisting direction S, the temperature of the second heater 205 C., and the second overfeed rate 2 percent) (Comparative Example 2); and the overfeed rate was adjusted to 6 percent in Comparative Example 2 (comparative Example 3). The properties of the treated yarns and their tension at the outlet of the second heater were compared as shown in Table 2 below.

Table 2 Residual Crimp Tension torque shrinkage (g/de) Remarks Example 9 4 15.4 0.020 Comp. Ex.1 35 16.3 0.017 Comp. Ex.2 8 7.2 0.080 Comp. Ex.3 Yarn breakage frequent; impossible to continue processing As is seen from Table 2, there is no substantial difference in crimp shrinkage between Example 9 and Comparative Example 1, but a drastic difference in residual torque is observed between them. in Example 9, a substantially nontorque yarn was obtained, whereas the yarn obtained in Comparative Example 2 has a large residual torque.

Furthermore, it is seen that in Comparative Example 2, the residual torque of the residual torque was reduced in the yarn of Comparative Example 2, but the crimp shrinkage is half as low as that of the yarn of Example 9.

The bulky yarn according to the present invention has a markedly reduced residual torque as compared with the conventional method, and its bulkiness is almost the same as that of the conventional bulky yarns. Therefore, when the yarn of the present invention is used for knitting, snarls do not occur. The knittability of the yarn obtained by the invention is very good, and the final knitted product obtained has great bulkiness.

EXAMPLE 10 AND COMPARATIVE EXAMPLE 4 The procedure of Example 1 was repeated except that a polyethylene-terephthalate yarn (Semi Dull) of 50 denier and 24 filaments was used, the first overfeed rate was 5 percent, the yarn speed was 85 meters/min, the number of twists was 3900 (T/M), the false-twisting direction was Z (S), the temperature of the first heater was 220 C., the second overfeed rate was 15 percent, the temperature of the second heater was 180 C., and a fluid nozzle capable of rotating the yarn in the same direction as the false-twisting direction [the yarn rotating direction 2 (S)], and the pneumatic pressure was 0.4 kglcm G.

For comparative purpose, the properties of the yarn which had been just subjected to the steps of twisting, heat-setting, and untwisting are shown in Table 3.

Table 3 Residual torque Crimp shrinkage Example 10 84 31.2 Comparative Example 4 53 35.1

It is seen that the bulky yarn obtained according to the present has a remarkably large residual torque and is best suited for application as de chin, etc.

EXAMPLES 11 to 18 The procedure of Example 1 was repeated except that the temperature of the first heater was 205 C., the temperature of the second heater was 220 C., the pneumatic pressure was 0.10 kg/cm G, and the second overfeed rate was changed as shown in Table 4 below. The results are shown in Table 4.

' It is seen from Table 4 that with increasing second overfeed rates, the yarn tension at the second heater is reduced, and the yarn can be maintained in a substantially relaxed condition. No remarkable difference in residual torque and crimp shrinkage was observed at this time.

COMPARATIVE EXAMPLES 5 TO 8 The procedure of Example 11 was repeated except that the second overfeed rate was changed as shown in Table 5.

Table 5 Second Tension of the Crimp Comparative overfeed yarn in the Residual shrinkage Examples rate(%) second heater torque EXAMPLES 19 TO 24 value.

Table 6 Examples 0 Residual torque Crimp shrinkage R E R 19 90 7.2 12.4 1.7 20 120 6.7 v 9 12.5 1.5 21 135 6.4 7 12.4 1.0 22 I65 6.3 6 l2.6 0.9 23 H0 6.2 5 l2.8 0.6 24 180 6.2 5 12.8 0.6

The yarn obtained was knitted on a l8-gauge circular knitting machine, and then scoured and dyed. The product had good surface condition and feeling and no dyeing unevenness was observed.

COMPARATIVE EXAMPLE 9 The procedure of Example 19 was repeated except that a guide and a fluid nozzle were provided at the sec- 0nd heater so that they passed through the center of the heater. The resulting yarn had a residual torque of 3.3 (f) and 35 (R). There was a marked deviation in residual torque among the spindles.

COMPARATIVE EXAMPLES 10 TO 12 The procedure of Example 19 was repeated except that 6 was changed as indicated in Table 7. The results are shown in Table 7.

Table 7 Comparative Residual torque Crimp shrinkage Examples 0 3? R i R 10 0 21.3 22 10.6 2.5 l l 45 9.6 15 l 1.5 2.3 12 7.9 1 1 12.0 1.9

EXAMPLES 25 AND 26 The procedure of Example 19 was repeated except that a polyethylene-terephthalate yarn (semidull; 50 denier/24 filaments) was crimped at a first overfeed rate of 5 percent, and a yarn speed of meters/min. with the number of false-twists of 3,900 T/M in the S direction while the temperature of the first heater was being maintained at 220 C.; and subsequently, the crimped yarn was treated in the same way as in Example 19 at a second overfeed rate of 15 percent and a pneumatic pressure at the nozzle of 0.4 kg/cm G while the temperature of the second heater was being maintained at C. (yarn rotating direction S; the angle was changed as indicated in Table 8.

Table 8 Residual torque (times/0.25 M) Crimp shrinkage(%) E R I R Examples 7' 0( COMPARATIVE EXAMPLES 13 AND 14 Table 9 .vcompal'ative Residual torque Examples Angle 0 (times/1.25 M) Crimp shrinkage(%) E R E R EXAMPLES 27 TO 42 The procedure of Example 24 was repeated except as noted below:

The second heater: a pipe heater provided with guides at its inlet and outlet such as shown in FIG. 7

The temperature of the second heater: 215 C.

The distance l,(cm): as shown in Table 10 in FIG. IV

The angle 0 as shown in Table 10 The distance 1 4.0 cm between the center of the nozzle The fluid nozzle: provided at the position at which the angle is O.

The results obtained are shown in Table 10 below.

Table 10 Table 13 Residual Tension of yarn Examples Distance ((2) (cm) Residual torque (5) Examples [,(cm) 0,() torqueli) at second heater 5 47 10 9.2 27 1 10.4 0.020 48 15 05 211 1.0 10.11 0.022 49 20 9.3 2) 1.0 10.6 0.021 50 30 7 3 30 1.0 13.4 0.021 31 1.5 5 9.5 0.020 32 1.5 10 9.11 0.018 g; {-2 if; 2 8-8;? 10 COMPARATIVE EXAMPLES AND 26 3 3; 88:2 The procedure of Example 47 was repeated except 37 3:0 15 917 01018 that the distance was changed as shown in Table 14. 38 3.0 20 11.9 0.020 39 38 5 82 0020 5 The results are shown 1n Table 14. 40 3.8 10 8.7 0.020 1 41 3.8 15 8.5 0.018 Table 14 42 3.8 20 8.9 0.020

Comparative Examples Distance I (cm) Residual torqueCr) 25 1.3 COMPARATIVE EXAMPLES 15 TO 24 20 26 10- The procedure of Example 27 was repeated except that the distance and the angle 6 were changed as EXAMPLES 51 TO 55 shown in Table 11. The results obtained are shown in Table 11. The procedure of Example 36 was repeated except Table 1] Comparative Residual Tension at the Examples [,(cm) 0() torqucLT) second heater Remarks (gr/dc) I5 08 S 12.3 0.024 Rotation of yarn 16 1.0 0 l .0 0.016 unstable 17 1.0 25 13.7 0.023 18 1.0 30 17.8 0.025 19 3.0 0 3.8 0.017 20 3.0 25 13.4 0.022 21 3.0 30 17.9 0.025 22 3.8 0 8.5 0.017 23 3.11 25 13.3 0.020 24 3.8 30 16.4 0.022

EXAMPLES 43 TO 46 The procedure of Example 27 was repeated except that the distance 1 was 3.0 cm, the angle 0 was 10, and the pneumatic pressure was changed as indicated in Table 12. The results obtained are shown in Table 12.

EXAMPLES 47 TO 50 The procedure of Example 43 was repeated except that the pneumatic pressure was 0.20 kg/cm G, and the 65 distance was changed as shown in Table 13. The results are shown in Table 13.

that the angle was varied as shown in Table 15. The results are shown in Table 15.

Table 15 Example 0 C) Residual Tension at the torque (3) second heater (g /dc) COMPARATIVE EXAMPLES 27 AND 28 The procedure of Example 36 was repeated except that the angle 0 was changed as shown in Table 16. The results are shown in Table 16.

Table 16 Comparative Residual Tension at second Examples 9 torque (is) heater (g/de) The procedure of Examples 36 was repeated except as noted below:

1. Temperature of the first heater was 220 C.

2. Temperature of the second heater was changed as shown in Table 17.

3. The ratio of the sectional area of the twisting path to that of a fluid flow was 11:1.

4. The diameter of the twisting path was 2.5 mm.

5. The fluid steam intersects the twisting path in a direction at right angles to the path and flows in a tangential direction with respect to the twisting path.

6. A fluid nozzle of the type shown in FIG. 2 was used, and by changing the air velocity, the Reynolds number in the twisting path of the fluid nozzle was changed as shown in Table 17.

Table 17 Temperature of Reynolds Residual Crimp Examples second heater number torque shrinkage COMPARATIVE EXAMPLES 29 TO 40 The procedure of Example 56 was repeated except that the temperature of the second heater and the Reynolds number were changed as indicated in Table 18. The results are shown in Table 18. The Reynolds numbers in these Comparative Examples were outside the scope of the present invention.

EXAMPLES 68 TO 79 The procedure of Example 56 was repeated except that the temperature of the first heater was adjusted to 200 C., and the temperature of the second heater and the Reynolds number were changed as shown in Table 19. The Reynolds numbers were all within the scope of the present invention.

Table 19 Temperature of Reynolds Residual Crimp Examples second heater number torque shrinkage COMPARATIVE EXAMPLES 41 TO 52 The procedure of Example 68 was repeated except that the temperature of the second heater and the Reynolds number were changed as shown in Table 20. The results are shown in Table 20. The Reynolds numbers were all outside the scope of the present invention.

EXAMPLES 80 TO The procedure of Example 56 was repeated except that the temperature of the second heater was adjusted to 205 C., and the Reynolds number and the second overfeed rate were changed as shown in Table 12. The Reynolds numbers were all within the scope of the present invention. The results are shown in Table 21.

Table 21 Second over- Reynolds Residual Crimp Examples feed rate number torque shrinkage EXAMPLES 86 TO 89 The procedure of Example 80 was repeated except that the second overfeed rate was 17 percent, and the temperature of the second heater, the speed of the yarn and the Reynolds number were changed as shown in within the scope of the present invention. The results Table 22. The results obtained are shown in Table 22. obtained are also shown in Table 25. The Reynolds numbers were all within the scope of the Table 25 present invention.

Table 2 Diameter of twist Residual Crimp Examples ing path (mm) torque shrinkage Yarn speed at the Crimp 2.0 4 14 Examples inlet of feed roller Reynoldss Residual Shrink- 3g 0 (meters/min.) number torque age l0] 5 l5 86 85 2,500 12 13.3 m 87 85 3.000 18 137 88 105 2,500 9 1244 89 105 3,000 -18 12.6 EXAMPLES 102 AND 103 The procedure of Example 72 was repeated except 5 that the fluids shown in Table 26 were used instead of Examples 90 TO 98 air. The Reynolds numbers were all within the scope of the present invention. The results obtained are The procedure of Example 80 was repeated except Shown in Table 26 that the polyethylene-terephthalate yarn (Semi-dull),

the temperatures of the first and second heaters, the Table' 26 number of twists, and the Reynolds number were changed as indicated in Table 23. The Reynolds num- Examples Pluids Residual torque Crimp shrinkage her were all within the scope of the present invention. 102 3 103 Carbon dioxide 5 15.1 The results obtained are shown 1n Table 23.

heater heater COMPARATIVE EXAMPLES 53 TO 58 EXAMPLE 104 The procedure of Example was repeated except that the polyethylene'terephthalate y (semi-dun), 45 In accordance with the procedure of Example 56, a

the temperatures of the first and second heaters, the p01y caproamide yam (semi n '70 denier/24 m number of tw1sts, and the Reynolds number were chanments) was crimped at a fi t f d rate f Zero pep ged as indicated in Table 24. The Reynolds numbers cent and a yarn speed of meters per minute with were all outside the scope of the present invention. The the number of false twists of 3180 T/M in the Z direcresults obtained are shown in Table 24. 50 tion while the temperatureof the first heater was main- Table 24 Temper- Temper- Com puru- Number uture zlture Number Reynolds Resi- Crimp live Denier of 01' 01 of number dual shrin Examples 0111- first second twists torque kagc meut lie-titer heater 53 I25 24 212 220 3070 I000 28 11.7 54 24 212 220 3070 3500 30 l2.4 55 I00 24 2 l 5 220 2960 i000 32 l L6 56 100 24 215 220 2960 3500 27 ll.0 57 75 24 215 200 3370 1000 40 13.6 58 75 24 215 200 3370 3750 34 13.0

EXAMPLES 99 TO 101 tained at C. Thereafter, the yarn was treated in the same way as set forth in Example 56 except that the The procedure of Example 72 was repeated except second overfeed rate was changed to 16 percent, the that the diameter of the twisting path was changed as temperature of the first heater was adjusted to (1., indicated in Table, 25. The Reynolds numbers were all and the Reynolds number was set at 2,000. The res u lt ing processed yarn had a residual torque of 12 and a crimp shrinkage of 14.1 percent. The Reynolds number was within the scope of the present invention.

COMPARATIVE EXAMPLES 59 AND 60 The procedure of Example 104 was repeated except that the Reynolds number was changed as shown in Table 27. The results are shown in Table 27. The Reynolds numbers were all outside the scope of the present invention.

Table 27 Comparative Reynolds Residual Crimp Examples number torque shrinkage EXAMPLE 105 The procedure of Example 104 was repeated except that a 50 de/12 fil semi-dull filament yarn of polyepsiloncaproamide was processed under the following conditions:

First overfeed rate:

Number of false twists: 3670 T/M Second overfeed rate:

Reynolds number: 2,000 (within the scope defined in claim 16) The resulting yarn had a residual torque of 8.

The 106 AND 107 AND COMPARATIVE EXAM- PLES 61 AND 62 A 70 de/24 fil semidull yarn was processed under the following conditions:

First overfeed rate: 0

Yarn speed: 100 meters/min. Number of false twists: 3180 T/M False-twisting direction: 2

Temperature of the first heater: 160C. Temperature of the second 190C.

heater:

Second overfeed rate: 16 Pneumatic pressure: 0.20 kg/cmG The results obtained are shown in Table 28.

What is claimed is:

l. A method of producing a bulky yarn having a controlled residual torque, which comprises subjecting a thermoplastic synthetic filament yarn to a series of twisting, heat-setting on a first heater, and untwisting; feeding the yarn into a second heater while rotating said yarn by means of a fluid nozzle; and re-heat-setting said yarn in the second heater, said yarn being maintained in a substantially relaxed state during the rotation by said fluid nozzle and said re-heat-setting by said second heater.

2. The method of claim 1, wherein rotation is imparted to said yarn by means of said fluid nozzle in a direction opposite to the twisting direction to thereby produce a substantially non-torque filament yarn.

3. The method of claim 1, wherein rotation is imparted to said yarn by means of said fluid nozzle in the same direction as the twisting direction to thereby produce a yarn having an increased residual torque.

4. The method of claim 1, wherein said yarn does not come into full contact with the wall surface of said second heater. v

5. The method of claim 1, wherein said yarn contacts said second heater only at its inlet and outlet ends.

6. The method of claim 1, wherein the yarn is maintained'under a tension lower than 0.070 g/denier during rotation by said fluid nozzle.

7. The method of claim 6, wherein the yarn is maintained under a tension lower than 0.050 g/denier during rotation by said fluid nozzle.

8. The method of claim 7, wherein the yarn is maintained under a tension lower than 0.025 g/denier during rotation by said fluid nozzle.

9. The method of claim 1, wherein said yarn is overfed to said second heater at an overfeed rate maintained at above 4 percent.

10. The method of claim 9, wherein the overfeed rate of the yarn to said second heater is maintained at above 6 percent.

11. The method of claim 10, wherein the overfeed rate of the yarn to said second heater is maintained at above 10 percent.

12. The method of claim 5, wherein the angles of said yarn with respect to the inlet and outlet ends of said second heater are selected so that when the inlet contact point and outlet contact point of said yarn at said second heater are projected on a cross-sectional plane perpendicular to the axis of said heater, the two projected points are connected by an arc of a circle or an ellipse, and an angle formed by connecting said two projected points with the center of said circle or ellipse is at least and when said are is a part of the arc of the ellipse, said ellipse has a long axis to short axis ratio of not more than 20:1.

13. The method of claim 5, wherein the yarn is treated under the following conditions:

l 30.0 cm 20 2 0. 2 0

wherein I is the distance between the point at which said yarn contacts the outlet of said second heater and the point at which the yarn passes to the center of said fluid nozzle inlet multiplied by cos 0,; 0, is an angle formed by the line joining the point at which said yarn contacts the outlet of said second heater with the point at which the yarn passes to the center of inlet of the inlet of the twisting path and the axial line of said second heater at the outlet contact end; is the distance between the point at which said yarn leaves the center of said fluid nozzle and the point at which the yarn is twist set multiplied by cos and 6 is an angle formed by the line joining the point at which the yarn leaves said fluid nozzle with the point at which the yarn is twist set and the axial line of said fluid nozzle at the outlet center thereof.

14. The method of claim 13, wherein 6 0.

15. The method of claim 1, wherein the yarn is rotated by a fluid of the Reynolds number greater than 1,000 and up to 5,000 at the twisting portion of said fluid nozzle.

16. The method of claim 2, wherein a fluid of the Reynolds number greater than 1,000 and satisfying the following equation (0.0433 T l5.13)(2.02 X lO )XDe- R 2 (0.040 T, 0.045 T 4.2)(0.877 X 10 De wherein T is a first heat-setting temperature (C), T

0.0450 T l4.90)(2.89 x 10 De a Re a 0.025 T, 0.0450 T s.40 2.0s rom 18. The method of claim 1, wherein the thermoplastic synthetic filament yarn has a denier of 15 to 300.

19. The method of claim 1, wherein the filament yarn is a polyethylene-terephthalate yarn, poly-epsiloncaproamide yarn or a mixed yarn thereof.

20. The method of claim 1, wherein said fluid is air,

nitrogen, carbon dioxide gas or mixtures thereof. 

1. A method of producing a bulky yarn having a controlled residual torque, which comprises subjecting a thermoplastic synthetic filament yarn to a series of twisting, heat-setting on a first heater, and untwisting; feeding the yarn into a second heater while rotating said yarn by means of a fluid nozzle; and re-heat-setting said yarn in the second heater, said yarn being maintained in a substantially relaxed state during the rotation by said fluid nozzle and said re-heat-setting by said second heater.
 2. The method of claim 1, wherein rotation is imparted to said yarn by means of said fluid nozzle in a direction opposite to the twisting direction to thereby produce a substantially non-torque filament yarn.
 3. The method of claim 1, wherein rotation is imparted to said yarn by means of said fluid nozzle in the same direction as the twisting direction to thereby produce a yarn having an increased residual torque.
 4. The method of claim 1, wherein said yarn does not come into full contact with the wall surface of said second heater.
 5. The method of claim 1, wherein said yarn contacts said second heater only at its inlet and outlet ends.
 6. The method of claim 1, wherein the yarn is maintained under a tension lower than 0.070 g/denier during rotation by said fluid nozzle.
 7. The method of claim 6, wherein the yarn is maintained under a tension lower than 0.050 g/denier during rotation by said fluid nozzle.
 8. The method of claim 7, wherein the yarn is maintained under a tension lower than 0.025 g/denier during rotation by said fluid nozzle.
 9. The method of claim 1, wherein said yarn is overfed to said second heater at an overfeed rate maintained at above 4 percent.
 10. The method of claim 9, wherein the overfeed rate of the yarn to said second heater is maintained at above 6 percent.
 11. The method of claim 10, wherein the overfeed rate of the yarn to said second heater is maintained at above 10 percent.
 12. The method of claim 5, wherein the angles of said yarn with respect to the inlet and outlet ends of said second heater are selected so that when the inlet contact point and outlet contact point of said yarn at said second heater are projected on a cross-sectional plane perpendicular to the axis of said heater, the two projected points are connected by an arc of a circle or an ellipse, and an angle formed by connecting said two projected points with the center of said circle or ellipse is at least 90*, and when said arc is a part of the arc of the ellipse, said ellipse has a long axis to short axis ratio of not more than 2.0:
 13. The method of claim 5, wherein the yarn is treated under the following conditions: l1 > or = 1.0 (cm) 20* > or = theta > 0*l2 < or = 30.0 cm 20* > or = theta 2 > or = 0* wherein l1 is the distance between the point at which said yarn contacts the outlet of said second heater and the point at which the yarn passes to the center of said fluid nozzle inlet multiplied by cos theta 1; theta 1 is an angle formed by the line joining the point at which said yarn contacts the outlet of said second heater with the point at which the yarn passes to the center of inlet of the inlet of the twisting path and the axial line of said second heater at the outlet contact end; l2 is the distance between the point at which said yarn leaves the center of said fluid nozzle and the point at which the yarn is twist set multiplied by cos theta 2; and theta 2 is an angle formed by the line joining the point at which the yarn leaves said fluid nozzle with the point at which the yarn is twist set and the axial line of said fluid nozzle at the outlet center thereof.
 14. The method of claim 13, wherein 15* > or = theta > 0*.
 15. The method of claim 1, wherein the yarn is rotated by a fluid of the Reynolds number greater than 1,000 and up to 5,000 at the twisting portion of said fluid nozzle.
 16. The method of claim 2, wherein a fluid of the Reynolds number greater than 1,000 and satisfying the following equation (-0.0433 T2 + 15.13)(2.02 X 102) X De0.200 > or = Re > or = (0.040 T1 - 0.045 T2 + 4.2)(0.877 X 102 De0.366) wherein T1 is a first heat-setting temperature (*C), T2 is a second heat-setting temperature (*C), and De is the denier size of the yarn, is introduced into the twisting portion of said fluid nozzle.
 17. The method of claim 16, wherein the Reynolds'' number is maintained at a value greater than 1,000 and satisfying the following equation: (-0.0450 T2 + 14.90)(2.89 X 102) De0.128 > or = Re > or = (0.025 T1 - 0.0450 T2 + 8.40)(2.08 X 102)De0.194
 18. The method of claim 1, wherein the thermoplastic synthetic filament yarn has a denier of 15 to
 300. 19. The method of claim 1, wherein the filament yarn is a polyethylene-terephthalate yarn, poly-epsilon-caproamide yarn or a mixed yarn thereof.
 20. The method of claim 1, wherein said fluid is air, nitrogen, carbon dioxide gas or mixtures thereof. 